The technology presented herein relates to an optical communication device and electronic equipment, and more particularly to an optical communication device and electronic equipment suitable for visible light communication, such as consumer-use devices incorporating visible light communication functions using LED lighting and vehicle-mounted devices incorporating visible light communication functions using LED signaling devices.
With development of high-performance and low-cost LEDs (Light Emitting Diodes), application of the LEDs to lighting equipment is rapidly spreading due to their characteristics of lower power consumption and long life. In these circumstances, visible light communication using the LEDs has also been proposed (see, e.g., JP 2004-221747 A).
A large number of methods have been proposed for the visible light communication including a method in which light receiving signals divided per optical wavelengths are transmitted for multi-channel communication (see, e.g., JP 2006-109461 A), a method in which a speech sound is subjected to AM modulation for transmission (see, e.g., JP 2004-193908 A), and a digital communication method involving four pulse position modulation. There are demands for small-size optical communication devices which implement these communication methods.
However, there has not yet been proposed any general-purpose device which supports all the methods and does not depend on a specific visible light communication method, and therefore it was necessary to prepare optical communication devices dedicated to a method to be used. For example, there is no optical communication device having both the analog output and the digital output, and in the case of using both the outputs by switching, it was necessary to mount both the output devices. Moreover, there is no optical communication device having an output which is divided into R, G, and B regions, and therefore, in order to transmit and receive different data sets in respective wavelength ranges of R, G, and B, some measures have been needed such as preparing three optical communication devices which receive signals of all the visible light wavelength ranges, and providing color filters to the entire surfaces of the respective optical communication devices.
Accordingly, a feature of an example embodiment presented herein is to provide an optical communication device and electronic equipment with versatility which can communicate in visible light wavelength ranges with a simple configuration regardless of the communication method.
In order to achieve the above feature, an optical communication device according to an aspect of the present embodiment comprises:
a one-chip light receiving element having a plurality of light receiving sections with light receiving sensitivity to different wavelength ranges in a visible light spectrum, wherein
the plurality of light receiving sections are divided into different light receiving section groups by the wavelength range to which the light receiving sections have the light receiving sensitivity,
the light receiving element has a light receiving surface divided into a plurality of blocks, and
light receiving sections in one light receiving section group having the light receiving sensitivity to an identical wavelength range are dispersedly placed in the respective blocks.
In the optical communication device with the above configuration, the light receiving sections in each light receiving section group, which have the light receiving sensitivity to an identical wavelength range, are dispersedly placed on the light receiving surface of the light receiving element, so that the light receiving sections of each light receiving section group are present in positions different from each other on the light receiving surface of the light receiving element, and therefore in the case of receiving the transmission light from the front side, the light receiving sections of each light receiving section group receive the transmission light, thereby achieving good reception performance. Moreover, even when transmission light coming obliquely from above the light receiving surface of the light receiving element is received and the transmission light does not strike upon the entire light receiving surface, the signal beam strikes upon at least a part of the respective light receiving sections of all the light receiving section groups, so that the reception limit angle in the oblique direction can be enlarged. Therefore, it becomes possible to realize an optical communication device with versatility which can communicate in visible light wavelength ranges with a simple configuration regardless of communication methods.
In one embodiment, the light receiving surface of the light receiving element is divided into a plurality of grid-like blocks, and the light receiving sections adjacent to each other along a row direction and a column direction of the light receiving element have the light receiving sensitivity to different wavelength ranges.
In this embodiment, in the state where the respective light receiving sections of each light receiving section group are dispersedly placed in the respective blocks, which are placed like grid on the light receiving surface of the light receiving element, the light receiving sections which are adjacent to each other along the row direction and the column direction have light receiving sensitivity to different wavelength ranges, so that the light receiving sections having the light receiving sensitivity to an identical wavelength range are not adjacent to each other but are dispersedly placed. Accordingly, in the case where transmission light coming obliquely from above the light receiving surface of the light receiving element is received and the transmission light strikes upon only a part of the light receiving surface, it becomes possible to ensure that the signal beam strikes upon at least a part of the respective light receiving sections of all the light receiving section groups.
In one embodiment, among the plurality of light receiving sections of the light receiving element, light receiving sections in one light receiving section group having the light receiving sensitivity to an identical wavelength range are connected to each other via joints.
In the embodiment, among the plurality of the light receiving sections of the light receiving element, the light receiving sections in one light receiving section group, which have the light receiving sensitivity to an identical wavelength range, are connected to each other via the joint, by which light receiving signals in one light receiving section group can be gathered so that one light receiving signal can be extracted from the light receiving section group to the outside via an output terminal.
In one embodiment, there are a plurality of light receiving section groups, in each of which the light receiving sections have the light receiving sensitivity to an identical wavelength range, and the light receiving section groups are almost equal in a total area of the light receiving sections of the group.
In this embodiment, because the light receiving section groups are almost equal in the total area of the light receiving sections of the group, when the transmission light coming from the front side is received, the light receiving section groups corresponding to the respective wavelength ranges have equal reception areas to receive the transmission light. Thus, if the level of the transmission light for every wavelength range is identical, then output signals of an identical level can be acquired.
In one embodiment, there are three light receiving section groups, each of which has three light receiving sections having light receiving sensitivity to an identical wavelength range, wherein the light receiving surface of the light receiving element is divided into grid-like nine blocks of three rows and three columns, in which a first light receiving section group is placed at a block of first row first column, a block of second row second column, and a block of third row third column; a second light receiving section group is placed at a block of first row second column, a bloc of second row third column, and a block of third row first column, and a third light receiving section group is placed at a block of first row third column, a block of second row first column, and a block of third row second column.
In this embodiment, the light receiving surface of the light receiving element is divided into grid-like nine blocks in three rows and three columns, in which the light receiving sections in a first light receiving section group may be placed at a block of first row first column, a block of second row second column and a block of third row third column; the light receiving sections in a second light receiving section group may be placed at a block of first row second column, a bloc of second row third column and a block of third row first column; and the light receiving sections in a third light receiving section group may be placed at a block of first row third column, a block of second row first column and a block of third row second column. In this way, the light receiving section groups corresponding to three wavelengths can be placed dispersedly with efficiency.
In one embodiment, the optical communication device has a condenser lens provided above the light receiving element for condensing an external light beam to a plurality of light receiving sections.
In this embodiment, the light beam from the outside is condensed to the light receiving sections with use of the condenser lens provided above the light receiving element, so that the light receiving surface of the light receiving element can efficiently receive the transmission light, and thereby the communication distance can be increased.
In one embodiment, the tight receiving element is configured to output a plurality of light receiving signals, said light receiving signals having undergone photoelectric conversion per every light receiving section group which has light receiving sensitivity to the identical wavelength range. The optical communication device further comprises a receiving integrated circuit for converting the plurality of light receiving signals from the light receiving element and outputting the signals as intended output signals.
In this embodiment, a plurality of light receiving signals from the light receiving element are converted by the receiving integrated circuit and outputted as intended output signals, which makes it possible to obtain a light receiving signal for every light receiving section group of which the component light receiving sections have sensitivity to light of an identical wavelength range.
In one embodiment, the receiving integrated circuit outputs the plurality of light receiving signals received from the light receiving element to outside as digital signals.
In this embodiment, a plurality of light receiving signals or the light receiving element are outputted from the receiving integrated circuit to the outside as digital signals, so that the device becomes easily applicable to the digital communication system.
In one embodiment, the receiving integrated circuit outputs the plurality of light receiving signals received from the light receiving element to outside as analog signals.
In this embodiment, a plurality of light receiving signals of the light receiving element are outputted from the receiving integrated circuit to the outside as analog signals, so that the device becomes easily applicable to the analog communication system.
In one embodiment, the receiving integrated circuit is configured to output the plurality of light receiving signals received from the light receiving element to outside as digital signals and also as analog signals.
In this embodiment, a plurality of light receiving signals of the light receiving element are outputted from the receiving integrated circuit to the outside as digital signals and analog signals, so that the device becomes applicable to both the digital communication system and the analog communication system. Thus, the versatility of the device is enhanced.
In one embodiment, the receiving integrated circuit has a switching section for, in response to a signal selection signal received from outside, selecting whether to output each of the plurality of light receiving signals received from the light receiving element as an analog signal or as a digital signal.
In this embodiment, the switching circuit is configured to select, in response to a signal selection signal from the outside, whether each light receiving signal from the light receiving element should be outputted as an analog signal or as a digital signal, so that the device becomes applicable to both the digital communication system and the analog communication system, and thereby versatility of the device can be enhanced.
In one embodiment, in response to the signal selection signal, the switching section of the receiving integrated circuit selects collectively per the plurality of the light receiving signals whether to output the light receiving signals as analog signals or as digital signals.
In this embodiment, because the switching section selecting per the plurality of the light receiving signals whether to output the light receiving signals as analog signals or as digital signals, the device is applicable to both the digital communication system and the analog communication system. Thus, versatility of the device can be enhanced.
In one embodiment, the receiving integrated circuit has an output selecting section for selecting any one of a plurality of light receiving signals switched by the switching section in response to an output selection signal received from outside, and outputting the selected signal to the outside.
In this embodiment, selecting any one of a plurality of light receiving signals switched by the switching section in response to an output selection signal received from outside, and outputting the selected signal enables the reduction in number of output terminals, the downsizing of the optical communication device, and improvement in mounting reliability.
Electronic equipment according to another aspect of the present technology comprises the optical communication device according to any one of the above embodiments.
Due to the provision of the optical communication device, it is possible to realize electronic equipment that can, with simple structure, perform communications in the visible wavelength regions.
As is apparent from above, according to the present embodiment, it is possible to realize an optical communication device and electronic equipment with versatility which can communicate in visible light wavelength ranges with a simple configuration regardless of the communication method.